I wanted to experiment with flat roof structures also, and it seemed like the best way to do that would be with the Quad Deck panels (we also used these to cover the basement).  This is some explanation of how we did that.

First, the video.

The Video

The Basics

Quad deck is fancy formwork (Insulated Concrete Formwork, AKA ICFs) for pouring a concrete slab over an open space.  To increase strength of the final concrete structure, Quad deck shapes the concrete into Ibeams.  It also includes its own internal steel structure to help it resist deflection before the concrete cures.  The EPS (expanded polystyrene) foam is the tough 25 PSI stuff.

When installing, there are a few key concepts to be aware of.

First, you need to support the weight of wet concrete until it cures.  This means you will need secure shoring.  The brochures show fancy specialized equipment, but scaffolding and cross beams works also.  These need to be strong, so do a little math and make sure that your shoring can handle the load.

Second, the concrete is going to try and push the ICFs apart.  If it can separate them, it will just spill thru between them and you will have a huge mess.  Toe nailing screws thru the shoring cross beams and into the steel reinforcement in the ICFs can prevent them from moving apart.  The “experts” who installed my basement used drywall screws.  I had a much easier time using self tapping metal screws that could easily tap into the steel reinforcement in the Quad Deck.

Third, don’t forget you will need to remove the shoring later 😉  The guys who did my basement often put screws in at angles that were only possible if the Quad Deck wasn’t there.  That gave me quite a hassle.  Build your shoring from below so that it can be removed from below.

Fourth, keep in mind that the concrete needs to sit on the perimeter ledge.  You will be removing that shoring, so the concrete needs to be firmly distributing its weight on the ledge around the perimeter.  This means you need to remove all the insulation from the edge of the QuadDeck panels.  It is tempting to leave some and let the ICF overlap the edge a little, but every bit of the ledge covered by the ICF is a bit of the ledge not supporting the load.

Fifth, you will need to mind the gap.  After installing the quad deck.  you can use spray foam insulation to close up any gaps between the wall and the quad deck.  Remember from 4 that we don’t want any insulation on the ledge.

Sixth, following your rebar specs, and especially rebar for the bond beam around the perimeter, is critical for strength.  Concrete is terrible in tension, you need the rebar for any sort of flat floor to carry a load because that load inevitably creates tension, especially in the bottom of the Ibeams.

Seventh, this is a pour, so close all the sides…  Also, make sure that the perimeter wall is to the correct height for easy finishing, etc.  Don’t just mark the wall where they should fill to, trim it off if you can.

Maybe I’ll come back and add more later.

The Gallery

A pic is worth a thousand words and here are a bunch of pics.